1. Field of the Invention
The present invention relates to a steering apparatus which has a mechanism for tilt/telescopic adjustments of a steering column, which can be satisfactorily assembled with a vehicle body, and which can enhance the rigidity of the apparatus itself.
2. Description of the Related Art
Generally, various steering apparatuses having a tilt/telescopic adjustment mechanism are known. A general steering apparatus of this type has a structure including a fixed bracket fixed to a vehicle body side, an inner column that rotatably supports a steering shaft, a steering support that supports the inner column so as to be slidable in an axial direction, and fastening means for fastening the inner column with the steering support interposed by fastening the fixed bracket (see FIGS. 6A and 6B).
FIGS. 6A and 6B illustrate a conventional steering apparatus which forms a tilt/telescopic adjustment mechanism. The steering apparatus includes a lower shaft a that is positioned on a front side of a vehicle body and connected to the steering apparatus, an upper shaft b positioned on a rear side of the vehicle body with a steering wheel attached thereto, and a universal joint c that connects both shafts. In FIG. 6A, the upper shaft b includes a telescopic mechanism which is realized by a spline or the like and which allows the upper shaft b to extend and contract in a front-rear direction (axial direction) to perform telescopic adjustment.
The upper shaft b is accommodated in the inner column with a bearing interposed so as to be rotatable around the axial direction. During the telescopic adjustment, the upper shaft b only extends and contracts but the lower shaft a does not extend and contract. Thus, the lower shaft a and the universal joint c can maintain an approximately immovable state (see FIG. 6A).
As described above, a steering apparatus in which a telescopic mechanism is provided in an upper shaft and which includes a tilt/telescopic mechanism which enables telescopic adjustment is disclosed in Japanese Patent Application Publication No. 2010-254290. In Japanese Patent Application Publication No. 2010-254290, a bifurcated arm-shaped portion that plays a role of allowing an outer column to swing in an up-down direction for tilt adjustment is formed on a front side of the vehicle body. A linking portion d is formed between two arm-shaped pieces that form the bifurcated arm-shaped portion. A circular through-hole to which a bearing that supports the upper shaft b is attached is formed in the linking portion d.
That is, the steering apparatus has a structure in which the inner column and the upper shaft b only move telescopically in relation to the outer column, and the universal joint c that connects the upper shaft b and the lower shaft a is immovable during the telescopic adjustment. Thus, during the telescopic adjustment, the universal joint does not interfere with the linking portion d. Therefore, the linking portion d can be provided between the two arm-shaped pieces of the bifurcated arm-shaped portion without taking the operation of the lower shaft a into consideration, and the rigidity of the bifurcated arm-shaped portion can be improved.